The present invention relates to an electrical plug-in adapter for optional connection of a three-pin plug system with lateral grounding contacts to different nationally specific plugging systems with and without grounding contact in accordance with the introductory clause of Patent Claim 1.
Such an electrical plug-in adapter without a grounding contact is disclosed already in the German Patent DE 3601469. This known plug-in adapter is provided with a housing on whose outside periphery several plugging systems are disposed as well as with a socket receptacle supported for rotation in the housing and comprising electrical contacts that are adapted for connection to corresponding electrical of the respective plugging systems in rotational positions of the socket receptacle, which are each associated with the outside plugging systems. As this known plug-in adapter is designed only for two-pin plugs without grounding contact the application potential of the known plug-in adapter is limited in view of the great number of international systems.
The present invention is based on the problem of improving an electrical plug-in adapter of the general type outlined by way of introduction for the application with a comparatively larger number of plugging systems with and without grounding contact.
In accordance with the present invention this problem is solved with the features defined in Patent Claim 1. Preferred features for expedient improvements of the invention are defined in the dependent Patent Claims.
With the invention hence an electrical plug-in adapter is made available in which different national plugs are arranged on a polygonal housing whilst a standardised socket receptacle is inserted and supported for rotation in a central opening inside the housing. The socket receptacle is provided for a three-pin plugging system and presents, on its underside, resilient contact sockets for the two plug pins as well as a grounding contact bow, with all three contact elements being equipped with a resilient contact lug. The plug pins and grounding contacts, which are distributed along the periphery, are each provided with a contact area on their inner head end supported in the housing, which contact areas are distributed, in their turn, on two superimposed orbits on the periphery of the inner housing opening, with the two pole pins on the lower orbit and the grounding contact on the upper orbit being each disposed preferably in a uniform triangular relationship. By rotation on the adjustable socket receptacle, the three resilient contact lugs can be contacted with the three rigid contact areas of the plug pin array in a marked position on the respective desired plug so as to establish a direct plug-in connection of the three-pin plugging systems in the socket receptacle with a respectively different nationally specific plug-and-socket system. For safety reasons, the plug pins out of engagement remain electrically neutral while the socket receptacle seals or is locked in the respective socket position so as to ensure a stable and safe contact connection.
In accordance with the present invention, the functional principle of the two-pin plug in electrical appliances, which is known from the German Patent 3601469, is extended to sockets with grounding contact and two-pin plugs with the aim to accommodate a maximum number of different connection systems on the smallest adapter housing possible, with a combination of plugging systems expediently related to each other, such as the old British plugging system with round plug pins and the new system with rectangular pins.
Moreover, the Swiss and the Italian plugging system were expediently united to form a single-plug combination wherein a grounding contact pin, which is centrally disposed between the plug pins, is arranged for displacement so that the plug could be plugged in the respectively required position. Furthermore, it is expedient to combine the Home office plug with lateral grounding contacts with the central grounding contact in a manner known per se and standardised in compliance with CEE 7.
Another extension of the potential applications is provided insofar as an xe2x80x9cAmerica plugxe2x80x9d and a combined Italian/Swiss plug are equipped with fold-down grounding contact pins so as to permit an adaptation to two-pin sockets without grounding contact. In this solution moreover expedient provisions are made to the effect that a respective locking lever, which is so connected to the fold-down grounding contact pin, is inevitably pivoted via the grounding contact bow into the catchment region of the socket receptacle, when it is pivoted, so as to prevent reliably an illicit operation of electrical appliances with grounding contact plug connection on two-pin sockets.
In correspondence with another embodiment of the invention, for improvement of safety, moreover provisions are made on the plugged-in plug adapter in order to close the two plug pin openings in the socket receptacle with a preferably automatically closing locking mechanism that releases the pin openings only in the positions associated with the respective plugging system in the case of plug pins of the same length and/or of an identical type. With this provision, a safe protection against accidental contact is expediently achieved and thus an unintentional or unauthorised insertion of metal objects is prevented.
According to the inventive concept, the number of the various potential applications of the electrical plug-in adapter is increased by the provision that at least one of the plugging systems comprises a grounding contact pin supported for movement in the housing. This grounding contact pin may preferably be supported for displacement and/or for pivoting in the housing and creates, by the various possible positions of the grounding contact pin, expedient new combinations of contact pins matching with individual nationally specific plugging systems.
In accordance with a preferred embodiment of the invention, the grounding contact pin is shaped from a punched folded brass sheet material with a hollow inside space and has a peripheral surface with rounded and resilient sections, with the respective rounded and the respective resilient sections opposition each other. In correspondence with a preferred embodiment, the condition of a punched board made of brass sheet material is differently shaped in isolated areas and then folded into its final shape. Here resilient sections are preferably formed to have flexible tongues that can be moved from a laterally projecting position for the insertion of the contact pin into a round contact opening in the case of insertion into a rectangular contact opening into a position in the inside space. With this provision, it is possible to insert the grounding contact pin into both round and rectangular grounding contact openings or sockets, respectively, and establish a safe contact.
According to another preferred embodiment of the invention, the folded contact pin made of brass sheet material presents at least one bent guiding section that is guided in the housing for displacement between two spaced stops. The plugging system with this aforementioned folded contact pin is particularly well suitable for the connection to both the old British plugging system with round plug pins as well as the new British plugging system with rectangular pins.
For connection of the plug-in adapter to the Swiss and Italian plugging systems a single plug system is provided on the plug-in adapter housing according to a preferred embodiment of the invention, which provides for one central displaceable grounding contact pin made of a solid profile.
In correspondence with a further embodiment of the invention, the grounding contact pin is provided on its rear end with a guiding profile while it is displaceable via lateral pins in the housing in a direction orthogonal on the remaining contact pins, whilst, by contrast, the guiding profile is prevented from pivoting and locked outside the uppermost displaced position of the grounding contact pin in the housing by a housing stop.
In correspondence with another embodiment of the invention, provisions are made to the effect that in the event of pivoting the grounding contact pin can activate a locking lever locking the socket receptacle against plugging of a plug. This provision expediently ensures that electrical appliances that must definitely not be operated other than with a grounding contact cannot be connected to a two-pin socket without grounding contact.
In correspondence with an alternative embodiment of the invention, the contact pin of the plugging system for the old British plugging system with round plug pins and the new British system with rectangular pins is not shaped from a punched folded brass sheer material with a hollow interior space but is rather manufactured of two separate parts, with a resilient element with resilient tongues being attached on the hollow contact pin body. This entails advantages for both manufacture and assembly as well as mounting.
According to a further alternative embodiment of the invention, a plugging system with two flat plugs and a U-shaped grounding contact pin can be converted into an American plugging system by pivoting the grounding contact pin, with a modified locking lever being provided that engages, in its locking position, into the socket receptacle and prevents a grounding contact pin from being inserted into the socket receptacle, while it is disposed, in its inoperative position, outside the socket receptacle. In correspondence with the alternative embodiment, this locking lever is moved out of its inoperative position into the locking position by a pushing and pivoting movement, with provisions being preferably made for locking the grounding contact pin from pivoting by means of the looking lever in its inoperative position. The locking lever preferably presents a pivoting shaft that is supported in the housing and provides for a stopping profile for a contact pin cam in the inoperative position.
According to another embodiment of the invention, the locking lever is adapted for being inserted into a recess in the housing on the side of the edge on the socket receptacle above the grounding contact. With this provision, the operation of electrical appliances with grounding contact on two-pole sockets is reliably prevented for safety reasons because the locking lever, in its locking position, covers the grounding contact in the socket receptacle, with the insertion of two-pole plugs without grounding contact being possible, however.
In the aforementioned alternative embodiment of the invention with a locking lever that can be moved by a pushing and pivoting movement out of its inoperative position into the locking position, the plugging system for the Swiss and Italian plugs is modified to the effect that the grounding contact pin is no longer pivotable but only displaceable still because now only one locking lever is still provided in combination with the American plugging system.